Simplifying
-7x2 + 5x + -18 = 0
Reorder the terms:
-18 + 5x + -7x2 = 0
Solving
-18 + 5x + -7x2 = 0
Solving for variable 'x'.
Begin completing the square. Divide all terms by
-7 the coefficient of the squared term:
Divide each side by '-7'.
2.571428571 + -0.7142857143x + x2 = 0
Move the constant term to the right:
Add '-2.571428571' to each side of the equation.
2.571428571 + -0.7142857143x + -2.571428571 + x2 = 0 + -2.571428571
Reorder the terms:
2.571428571 + -2.571428571 + -0.7142857143x + x2 = 0 + -2.571428571
Combine like terms: 2.571428571 + -2.571428571 = 0.000000000
0.000000000 + -0.7142857143x + x2 = 0 + -2.571428571
-0.7142857143x + x2 = 0 + -2.571428571
Combine like terms: 0 + -2.571428571 = -2.571428571
-0.7142857143x + x2 = -2.571428571
The x term is -0.7142857143x. Take half its coefficient (-0.3571428572).
Square it (0.1275510204) and add it to both sides.
Add '0.1275510204' to each side of the equation.
-0.7142857143x + 0.1275510204 + x2 = -2.571428571 + 0.1275510204
Reorder the terms:
0.1275510204 + -0.7142857143x + x2 = -2.571428571 + 0.1275510204
Combine like terms: -2.571428571 + 0.1275510204 = -2.4438775506
0.1275510204 + -0.7142857143x + x2 = -2.4438775506
Factor a perfect square on the left side:
(x + -0.3571428572)(x + -0.3571428572) = -2.4438775506